Hello
I am building BVH input files for an AnyBody musculoskeletal model from IMU data (7 lower-body sensors), and I have a question about how the joint rotations in the MOTION section should be defined.
As I understand it, each joint channel in a BVH file holds an Euler-angle rotation relative to the parent joint. In my pipeline I can compute the joint angles in two ways:
Raw joint angles – the rotation between adjacent segments as measured by the IMUs, where a standing (static) pose does not necessarily give exactly zero.
Offset-corrected joint angles – the raw angles minus the angles measured during a static standing trial, so that the standing pose becomes zero by definition.
My question is: which of these should be written into the BVH file for AnyBody? In other words, does AnyBody expect the BVH rotations to be zero in the standing pose defined by the HIERARCHY offsets, or does it expect the "true" joint angles regardless of what the static trial gives?
Any advice or pointers to how others have handled this would be greatly appreciated.
Thank you.